Apparatus for managing a plating liquid

ABSTRACT

The concentration of a leveler in a plating liquid that is used by a plating apparatus for filling metal such as copper in interconnection trenches and holes defined in the surface of a semiconductor substrate or the like is determined based on a peak area (Ar value) in a peel-off region of the plating liquid measured according to a CV or CVS process.

TECHNICAL FIELD

The present invention relates to a method of measuring the concentrationof a leveler in a plating liquid that is used by a plating apparatus forfilling metal such as copper in interconnection trenches and holesdefined in the surface of a semiconductor substrate or the like, and amethod of and an apparatus for managing a plating liquid to manage thecomponents thereof.

BACKGROUND ART

For filling interconnection trenches and holes defined in the surface ofa semiconductor substrate or the like according to a copper sulfateelectroplating process, it is often customary to add three organicadditives, described below, to basic plating liquid components coppersulfate (CuSO4.5H2O), sulfuric acid (H2SO4), and chlorine (Cl) in orderto improve the qualities of a plated film and increase the fillability(embeddability) of trenches and holes.

One of the three organic additives is a carrier (also referred to as abrightener) for making the plated film dense and for increasing theluster of the plated film. The carrier generally comprises a sulfuriccompound (e.g., HS-CnH2n-SO3 Mercapto alkylsulfonic acid) and exists asan anion in a plating liquid. The carrier obstructs the deposition ofcopper ions and promotes the achievement of a finer structure of theplated film.

The second of the three organic additives is a polymer (also referred toas a suppressor or a carrier) for suppressing the deposition of adsorbedcopper ions on the surface of a cathode thereby to increase activatedpolarization for increased uniform electrodeposition. The polymergenerally comprises a surface-active agent such as PEG or PPG.

The third organic additive is a leveler comprising a nitrogen-containingcompound such as polyamine or the like. The leveler is present as acation in a plating liquid.

The leveler is adsorbed greatly in a region where the current density ishigh. In the region where the adsorption of the leveler is large, anactivation overvoltage increases to suppress the deposition of copper.At the bottom of fine trenches and holes, however, the adsorption of theleveler is smaller, resulting in a larger amount of the deposition ofcopper. The deposited state with the raised bottom represents anexcellent leveling capability.

The management of the concentration of additives in a plating liquid ofcopper sulfate is important in managing the qualities of a plated filmand the embeddability of trenches and holes. However, no process ispresently available for measuring the absolute concentration of a traceof organic compound in a strong acid.

The present general process of analyzing the concentration of additivesin a plating liquid is called a CV (Cyclic Voltammetric) process or aCVS (Cyclic Voltammetric Stripping) process. According to this process,the amount of copper deposited on a rotating cathode electrode ismeasured and converted into the concentration of an additive referred toas a deposition inhibitor or promoter.

In a plating solution of copper sulfate, however, only theconcentrations of the carrier and the polymer can be measured by theabove process, and the concentration of the leveler cannot be measuredby the above process. The concentration of the leveler is the smallestamong the concentrations of the above three additives. The leveler hasproperties similar to those of the polymer, and it has been said that itis impossible to measure the concentration of the leveler even accordingto the CV or CVS process.

A method of managing and adjusting the components of a plating liquidused by a plating apparatus of the type described above will bedescribed below. Consumed amounts of the components of a plating liquidare empirically determined when the plating apparatus starts to operatein a plating mode and also when the plating apparatus is operating in asteady mode. Depending on a quantity of electricity (current×time), aninitial startup replenishing liquid (starter) is added to a base platingliquid. In a subsequent operation, a replenishing liquid (replenisher)is appropriately supplied to manage and adjust the components of theplating liquid. The starter comprises additive component liquids mixeddepending on the consumed amounts of the components at the time ofstarting the plating apparatus. Similarly, the replenisher alsocomprises additive component liquids mixed depending on the consumedamounts of the components at the time of normal operation of the platingapparatus.

The empirical process has been used because it has been difficult toanalyze the concentrations of the additives. However, since it isdifficult to manage the concentrations accurately and the added amountsof the components are predetermined, this process finds it difficult tocope with a situation where the consumed amounts of the components arebrought out of balance due to time-depending changes in the platingconditions.

There has recently been proposed an automatic analyzing device forquickly analyzing and automatically measuring additives according to anelectrochemical process.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above difficulties.It is an object of the present invention to provide a method ofmeasuring the concentration of a leveler which is an additive in aplating liquid of copper sulfate, which has been impossible to measureaccording to a conventional CV or CVS process.

Another object of the present invention is to provide a method of and anapparatus for managing a plating liquid to automatically analyzeadditives of the plating liquid and adjust the components of the platingliquid based on the analyzed results.

In particular, a method of measuring the concentration of a leveler in aplating liquid of copper sulfate to measure the concentration of anadditive containing nitrogen, which is referred to as a leveler, amongorganic additives contained in an electroplating liquid of coppersulfate is provided. The concentration of the leveler in the platingsolution is determined based on a peak area (Ar value) in a peel-offregion of the plating liquid measured according to a CV or CVS process.

Alternatively, a method of measuring the concentration of a leveler in aplating liquid of copper sulfate to measure the concentration of anadditive containing nitrogen, which is referred to as a leveler, amongorganic additives contained in an electroplating liquid of coppersulfate is provided. The concentration of a brightener (carrier), and awetting agent or a polarizing agent (polymer), which are other organicadditives of the plating liquid, are analyzed. Thereafter, a calibrationcurve for the concentration of the leveler using a standard liquidprepared with the concentration of the carrier and the concentration ofthe polymer is generated. The concentration of the leveler of theplating liquid is determined based on a peak area (Ar value) in apeel-off region of the plating liquid measured according to a CV or CVSprocess.

As another alternative, a method of measuring the concentration of aleveler in a plating liquid of copper sulfate to measure theconcentration of an additive containing nitrogen, which is referred toas a leveler, among organic additives contained in an electroplatingliquid of copper sulfate is provided. A measuring liquid containing apromoting additive containing a sulfur-based material, which is referredto as a carrier, is prepared at a concentration that is 2 to 40 times astandard concentration. A difference in the amount of copper depositionon a rotary electrode according to a CV or CVS process is measured tocalculate the concentration of the leveler.

The performance of the leveler in the plating solution of copper sulfateis not determined by the concentration of the leveler alone, but isaffected by the concentrations of the carrier and the polymer.Particularly, the concentration of the carrier affects the levelingcapability. If a nondye nitrogen compound such as polyamine or the likeis used as the leveler, then the leveling nature becomes distinct,allowing a calibration curve to be drawn clearly, by increasing theconcentration of the carrier in the plating liquid to be analyzed,relatively 2 to 40 times.

As another alternative, a method of measuring the concentration of aleveler in a plating liquid of copper sulfate to measure theconcentration of an additive containing nitrogen, which is referred toas a leveler, among organic additives contained in an electroplatingliquid of copper sulfate is provided. The plating liquid is passedthrough an organic anion-selective adsorption film to remove thepromoting additive containing a sulfur-based material, which is referredto as a carrier, from the plating liquid. Thereafter, a difference in anamount of copper deposition on a rotary electrode is measured accordingto a CV or CVS process to calculate the concentration of the leveler.

If a nitrogen compound such as yanus green is used as the leveler, thenthe leveling nature becomes distinct, allowing a calibration curve to bedrawn clearly, by bringing the amount of carrier closely to zero.Therefore, by passing the plating liquid through the organicanion-selective adsorption film, the carrier can be removed from theplating liquid, and a calibration curve can be drawn clearly.

Another method of managing a plating liquid includes sampling, at apredetermined interval, a predetermined amount of plating liquid in aplating apparatus which immerses a substrate to be plated in the platingliquid to plate a surface of the substrate. Components of the sampledplating liquid are analyzed with an automatic analyzing device, andcomponent replenishing liquids comprising components of the platingliquid are supplied to the plating liquid based on analyzed resultsand/or the number of substrates to be plated and a quantity ofelectricity consumed to plate the substrates for thereby managing thecomponents of the plating liquid. The component replenishing liquidscomprise a standard liquid, a plurality of solutions of a basic liquidwith a plurality of different additives added thereto, sulfuric acid,and hydrochloric acid, either wholly or partly, and the componentreplenishing liquids are supplied to the plating liquid for therebyindividually replenishing and managing the components of the platingliquid.

In the above method, the basic liquid comprises a solution of at leastcopper sulfate (CuSO4.5H2O), and sulfuric acid (H2SO4), mixed atpredetermined ratios. The standard liquid comprises a solution of thebasic liquid, and the plurality of additives and hydrochloric acid addedthereto at predetermined ratios.

A total amount of component replenishing liquids to be supplied to theplating liquid can be substantially the same as a reduction in theplating liquid which is caused by plating the substrate.

An apparatus is provided for managing the components of a plating liquidin a plating apparatus which immerses a substrate to be plated in theplating liquid in a plating tank to plate a surface of the substrates.The apparatus includes a plating liquid sampling device for sampling apredetermined amount of the plating liquid at a predetermined interval,an automatic analyzing device for automatically analyzing the componentsof the plating liquid sampled by the plating liquid sampling device, anda component replenishing liquid supply device for supplying componentreplenishing liquids comprising the components of the plating liquid.The component replenishing liquids are supplied to the plating liquidbased on analyzed results from the automatic analyzing device and/or thenumber of substrates to be plated and a quantity of electricity consumedto plate the substrates for thereby managing the components of theplating liquid. The component replenishing liquids comprise a standardliquid, a plurality of solutions of a basic liquid with a plurality ofdifferent additives added thereto, sulfuric acid, and hydrochloric acid,either wholly or partly, and the component replenishing liquids aresupplied by the component replenishing liquid supply device to theplating liquid for thereby individually replenishing and managing thecomponents of the plating liquid.

In the above apparatus, the basic liquid comprises a solution of atleast copper sulfate (CuSO4.5H2O), and sulfuric acid (H2SO4), mixed atpredetermined ratios. The standard liquid comprises a solution of thebasic liquid and the plurality of additives and hydrochloric acid addedthereto at predetermined ratios.

The apparatus described above can include a plating liquid adjustingtank, separate from the plating tank, for supplying the componentreplenishing liquids to the plating liquid.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing an arrangement of an apparatus for carryingout a method of measuring the concentration of a leveler in a platingliquid according to the present invention;

FIG. 2 is a diagram showing the relationship between the concentrationof a leveler and the calibration curve for Ar values; and

FIG. 3 is a diagram showing an arrangement of a plating liquid managingapparatus for carrying out a method of managing the components of aplating liquid according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will hereinafter be describedwith reference to the drawings. FIG. 1 is a diagram showing anarrangement of an apparatus (automatic analyzing device) for carryingout a method of measuring the concentration of a leveler in a platingliquid of copper sulfate according to the present invention. In FIG. 1,the apparatus has a measurement cell 10 housing therein rotary diskelectrodes 12 held by an electrode holder 11 and a stirring impeller 13that can be driven in a contactless manner by a stirrer 14. Apotentiostat 15 for automatically adjusting currents to bring thepotentials between the electrodes into a desired setting is connected tothe electrode holder 11.

A low-concentration basic liquid tank 21 holds a low-concentration basicliquid Q1 therein. A high-concentration basic liquid tank 22 holds ahigh-concentration basic liquid Q2 therein. A checking liquid tank 23holds a checking liquid Q3 therein. A first additive liquid tank 24holds an additive A (polymer) liquid Q4 therein. A second additiveliquid tank 25 holds an additive B (carrier) liquid Q5 therein. A thirdadditive liquid tank 26 holds an additive C (leveler) liquid Q6 therein.A standard liquid tank 27 holds a standard liquid Q7 therein. The basicliquid comprises a solution of copper sulfate (CuSO4.5H2O), and sulfuricacid (H2SO4), mixed at predetermined ratios. The standard liquidcomprises a solution of the basic liquid and a plurality of additivesand hydrochloric acid that are added thereto at predetermined ratios.The checking liquid comprises a solution for checking the polymer, thesolution containing the basic liquid and a certain amount of additivemixed therewith.

A burette 29 is connected to the low-concentration basic liquid tank 21through a three-way valve 28 for extracting a certain amount oflow-concentration basic liquid Q1 from the low-concentration basicliquid tank 21 and supplying the extracted amount of low-concentrationbasic liquid Q1 into the measurement cell 10. Burettes 31, 33, 35, 37,39, 41 are connected respectively to the high-concentration basic liquidtank 22, the checking liquid tank 23, the additive liquid tank 24, theadditive liquid tank 25, the additive liquid tank 26, and the standardliquid tank 27 through respective three-way valves 30, 32, 34, 36, 38,40 for supplying certain amounts of high-concentration basic liquid Q2,checking liquid Q3, additive A liquid Q4, additive B liquid Q5, additiveC liquid Q6, and standard liquid Q7, and for supplying the extractedamounts of high-concentration basic liquid Q2, checking liquid Q3,additive A liquid Q4, additive B liquid Q5, additive C liquid Q6, andstandard liquid Q7 into the measurement cell 10.

A controller 42 comprising a CPU controls a driver 43 for switching thethree-way valves 28, 30, 32, 34, 36, 38, 40 and activating andinactivating the burettes 29, 31, 33, 35, 37, 39, 41 depending on apolymer concentration measuring mode, a carrier concentration measuringmode, and a leveler concentration measuring mode, described below, andalso controls various other parts.

A sample tank 44 holds a sample plating liquid whose concentration is tobe measured. The sample plating liquid flows from a sample inlet port 45into the sample tank 44, overflows the sample tank 44, and returns froma sample return port 46 to a plating apparatus (not shown). A samplenozzle 47 is positioned above the sample tank 44 and is connected to aburette 48 through a three-way valve 49. The burette 48 extracts acertain amount of sample plating liquid from the sample tank 44 via thesample nozzle 47. After the sample nozzle 47 is moved to a position overthe measuring cell 10, the burette 48 supplies the extracted sampleplating liquid into the measuring cell 10.

A pump 51 for delivering pure water is connected to the burette 48 andthe sample nozzle 47 via the three-way valve 49 to wash them. Theinterior of the measurement cell 10 is also washed by pure water. Thesolution in the measurement cell 10 is drained by a pump 50.

The polymer concentration measuring mode for measuring a polymerconcentration, the carrier concentration measuring mode for measuring acarrier concentration, and the leveler concentration measuring mode formeasuring a leveler concentration, which are carried out by theconcentration measuring apparatus thus constructed, will be describedbelow by way of example.

[Polymer Concentration Measuring Mode]

First, it is confirmed that the electrodes 12 are stable by extracting50 ml of low-concentration basic liquid Q1 from the low-concentrationbasic liquid tank 21, supplying the extracted low-concentration basicliquid Q1 to the measurement cell 10, determining an Ar value, i.e., apeak area (time×current density=quantity of electricity) in a peel-offregion according to the CVS process, and deciding whether the Ar valueis an appropriate value or not. If the Ar value is not an appropriatevalue, the low-concentration basic liquid Q1 is drained from themeasurement cell 10, the measurement cell 10 is washed, 50 ml oflow-concentration basic liquid Q1 is again extracted, the extractedlow-concentration basic liquid Q1 is supplied to the measurement cell10, and the above cycle is repeated.

If the Ar value is an appropriate value, then 1 ml of checking liquid Q3is extracted from the checking liquid tank 23 and supplied to themeasurement cell 10, and an Ar value is measured according to the CVSprocess. The cycle of extracting and supplying the checking liquid Q3and measuring an Ar value according to the CVS process is repeated apredetermined number of times (usually five times, at most 10 times) todraw a calibration curve. When the calibration curve has been drawn, theliquid in the measurement cell 10 is drained, and the interior thereofis washed.

Then, 50 ml of low-concentration basic liquid Q1 is extracted from thelow-concentration basic liquid tank 21 and supplied to the measurementcell 10, and it is decided whether an Ar value is an appropriate valueor not (to confirm that the electrodes 12 are stable). If the Ar valueis an appropriate value, then 1 ml of sample plating liquid (specimen)is extracted and added to the liquid in the measurement cell 10, and anAr value is measured according to the CVS process. The cycle ofextracting and supplying the sample liquid and measuring an Ar valueaccording to the CVS process is repeated a predetermined number of times(usually five times, at most 10 times) to draw a calibration curve. Whenthe calibration curve has been drawn, the liquid in the measurement cell10 is drained, and the interior thereof is washed.

A polymer concentration of the sample plating liquid is determined froma comparison between the above two calibration curves. Specifically,since the polymer concentration of the checking liquid Q3 is known, thepolymer concentration of the sample plating liquid can be determined bycomparing the calibration curve obtained from the checking liquid Q3 andthe calibration curve of the sample plating liquid.

[Carrier Concentration Measuring Mode]

As with the above polymer concentration measuring mode, it is confirmedthat the electrodes 12 are stable by extracting 50 ml oflow-concentration basic liquid Q1 from the low-concentration basicliquid tank 21, supplying the extracted low-concentration basic liquidQ1 to the measurement cell 10, measuring an Ar value according to theCVS process, and confirming that the Ar value is an appropriate value.

If it is confirmed that the Ar value is an appropriate value, then thelow-concentration basic liquid Q1 is drained from the measurement cell10 and the measurement cell 10 is washed. Thereafter, 48.5 ml ofhigh-concentration basic liquid Q2 is extracted from thehigh-concentration basic liquid tank 22, 1 ml of additive A liquid Q4 isextracted from the additive liquid tank 24, and 0.5 ml of additive Cliquid Q6 is extracted from the additive liquid tank 26. The extractedliquids are supplied to the measurement cell 10, and an Ar value ismeasured according to the CVS process. Then, 0.5 ml of additive B liquidQ5 is extracted from the additive liquid tank 25 and supplied to themeasurement cell 10, and an Ar value is measured according to the CVSprocess. The cycle of extracting 0.5 ml of additive B liquid Q5 from theadditive liquid tank 25 and supplying the extracted additive B liquid Q5to the measurement cell 10 and measuring an Ar value according to theCVS process is repeated a predetermined number of times (usually fourtimes) to draw a calibration curve. The measured data are determined,and if the measured data are appropriate, then the liquid in themeasurement cell 10 is drained and the interior of the measurement cell10 is washed.

Then, it is confirmed again that the electrodes 12 are stable byextracting 50 ml of low-concentration basic liquid Q1 from thelow-concentration basic liquid tank 21, supplying the extractedlow-concentration basic liquid Q1 to the measurement cell 10, measuringan Ar value according to the CVS process, and confirming that the Arvalue is an appropriate value.

If it is confirmed that the Ar value is an appropriate value, then thelow-concentration basic liquid Q1 is drained from the measurement cell10 and the measurement cell 10 is washed. Thereafter, 99.6 ml of sampleplating liquid is extracted and supplied to the measurement cell 10, and1 ml of additive A liquid Q4 is extracted from the additive liquid tank24 and added to the liquid in the measurement cell 10. An Ar value ismeasured according to the CVS process, and a carrier concentration ofthe sample plating liquid is measured from the calibration curve shownin FIG. 2 based on the measured Ar value.

[Leveler Concentration Measuring Mode]

A leveler concentration can be measured according to three methods.These leveler concentration measuring methods will be described below.

In an example of the leveler concentration measuring method according tothe invention, it is confirmed that the electrodes 12 are stable byextracting 100 ml of low-concentration basic liquid Q1 from thelow-concentration basic liquid tank 21, supplying the extractedlow-concentration basic liquid Q1 to the measurement cell 10, measuringan Ar value according to the CVS process, and confirming that the Arvalue is an appropriate value.

If it is confirmed that the Ar value is an appropriate value, then thelow-concentration basic liquid Q1 is drained from the measurement cell10 and the measurement cell 10 is washed. Thereafter, 48 ml ofhigh-concentration basic liquid Q2 is extracted from thehigh-concentration basic liquid tank 22, 1 ml of additive A liquid Q4 isextracted from the additive liquid tank 24, and 1 ml of additive Bliquid Q5 is extracted from the additive liquid tank 25. The extractedliquids are supplied to the measurement cell 10, and an Ar value ismeasured according to the CVS process.

Then, 0.1 ml of additive C liquid Q6 is extracted from the additiveliquid tank 26 and supplied to the measurement cell 10, and an Ar valueis measured according to the CVS process. The cycle of extracting 0.1 mlof additive C liquid Q6, supplying the extracted additive C liquid Q6 tothe measurement cell 10, and measuring an Ar value according to the CVSprocess is repeated a predetermined number of times (usually four times)to draw a calibration curve as shown in FIG. 2. The measured data aredetermined, and if the measured data are appropriate, then the liquid inthe measurement cell 10 is drained and the interior of the measurementcell 10 is washed.

50 ml of sample plating liquid is extracted and supplied to themeasurement cell 10, and an Ar value is measured according to the CVSprocess. A leveler concentration of the sample plating liquid ismeasured from the calibration curve shown in FIG. 2 based on themeasured Ar value. If the Ar value of the sample plating liquid isrepresented by y in FIG. 2, then the corresponding leveler concentrationis determined as x.

In a further leveler concentration measuring method, after it isconfirmed that the electrodes 12 are stable, a certain amount ofhigh-concentration basic liquid Q2 is extracted from thehigh-concentration basic liquid tank 22, and a certain amount ofadditive B liquid Q5 is extracted from the additive liquid tank 25 suchthat its concentration is 2 to 40 times the above concentration(high-concentration basic liquid Q2+additive B liquid Q5=50 ml). Theextracted liquids are supplied to the measurement cell 10, and an Arvalue is measured according to the CVS process.

Then, 0.1 ml of additive C liquid Q6 is extracted from the additiveliquid tank 26 and supplied to the measurement cell 10, and an Ar valueis measured according to the CVS process. The cycle of extracting 0.1 mlof additive C liquid Q6 and supplying the extracted additive C liquid Q6to the measurement cell 10 and measuring an Ar value according to theCVS process is repeated a predetermined number of times (usually fourtimes) to draw a calibration curve (not shown). The measured data aredetermined, and if the measured data are appropriate, then the liquid inthe measurement cell 10 is drained and the interior of the measurementcell 10 is washed.

50 ml of sample plating liquid is extracted and supplied to themeasurement cell 10, and an Ar value is measured according to the CVSprocess. A leveler concentration of the sample plating liquid ismeasured from the calibration curve based on the measured Ar value.

In a leveler concentration measuring method according to the presentinvention, after it is confirmed that the electrodes 12 are stable, 49ml of high-concentration basic liquid Q2 is extracted from thehigh-concentration basic liquid tank 22, and 1 ml of additive A liquidQ4 is extracted from the additive liquid tank 24. The extracted liquidsare supplied to the measurement cell 10, and an Ar value is measuredaccording to the CVS process.

Then, 0.1 ml of additive C liquid Q6 is extracted from the additiveliquid tank 26 and supplied to the measurement cell 10, and an Ar valueis measured according to the CVS process. The cycle of extracting 0.1 mlof additive C liquid Q6 and supplying the extracted additive C liquid Q6to the measurement cell 10 and measuring an Ar value according to theCVS process is repeated a predetermined number of times (usually fourtimes) to draw a calibration curve (not shown). The measured data aredetermined, and if the measured data are appropriate, then the liquid inthe measurement cell 10 is drained and the interior of the measurementcell 10 is washed.

50 ml of sample plating liquid from which the carrier has been removedby passing the plating liquid through an organic anion-selectiveadsorption film is extracted and supplied to the measurement cell 10. AnAr value is measured according to the CVS process, and a levelerconcentration of the sample plating liquid is measured from thecalibration curve based on the measured Ar value.

With a number of leveler calibration curves for different carrier andpolymer concentrations being stored in the computer of the controller42, the concentration measuring apparatus of the above construction iscapable of analyzing samples easily within a short period of time.

According to the above methods of measuring the concentration of aleveler, it is possible to measure the concentration of a leveler in aplating liquid, which could not heretofore be measured according to theCV or CVS process.

FIG. 3 is a diagram showing an arrangement of a plating liquid managingapparatus which incorporates the automatic analyzing device for platingliquids shown in FIG. 1. The plating liquid managing apparatus has aplating tank 110 holding a plating liquid Q therein. An anode electrodeplate 111 and a substrate 112 to be plated are placed in the platingtank 110 so as to confront (face) each other. When a plating current issupplied between the anode electrode plate 111 and the substrate 112 tobe plated from a plating power supply E, the surface of the substrate112 is plated according to an electroplating process.

A plating liquid adjusting tank 113 for adjusting a plating liquid canbe supplied with a standard liquid Q11 from a standard liquid tank 114through a pump P1 and a valve V1, a replenishing liquid Q12, whichcomprises the basic liquid and the additive A mixed therein, from afirst replenishing liquid tank 115 through a pump P2 and a valve V2, areplenishing liquid Q13, which comprises the basic liquid and theadditive B mixed therein, from a second replenishing liquid tank 116through a pump P3 and a valve V3, a replenishing liquid Q14, whichcomprises the basic liquid and the additive C mixed therein, from athird replenishing liquid tank 117 through a pump P4 and a valve V4,sulfuric acid (H2SO4) Q15 from a sulfuric acid tank 118 through a pumpP5 and a valve V5, and hydrochloric acid (HCl) Q16 from a hydrochloricacid tank 119 through a pump P6 and a valve V6.

A plating liquid Q17 which has been adjusted in the plating liquidadjusting tank 113 is supplied to the plating tank 110 through a filter120 by a pump P7. The plating liquid Q in excess of a certain level inthe plating tank 110 is returned to the plating liquid adjusting tank113. Therefore, the plating liquid circulates between the plating liquidadjusting tank 113 and the plating tank 110.

The plating liquid Q7 supplied to the plating tank 110 is sampled by asampling device 121. The components of the plating liquid Q17 sampled bythe sampling device 121 are automatically analyzed by an automaticanalyzing device 122. The plating liquid managing apparatus has a draintank 123, and a level sensor 124 for measuring a plating liquid level inthe plating liquid adjusting tank 113, and a controller 125.

The controller 125 receives the analyzed results of the components ofthe plating liquid 17 analyzed by the automatic analyzing device 122 andthe plating liquid level measured by the level sensor 124. Based on theanalyzed results of the components of the plating liquid Q17 analyzed bythe automatic analyzing device 122, the controller 125 controls thepumps P1-P6 and the valves V1-V6 to control the standard liquid Q11supplied from the standard liquid tank 114, the replenishing liquid Q12supplied from the replenishing liquid tank 115, the replenishing liquidQ13 supplied from the replenishing liquid tank 116, the replenishingliquid Q14 supplied from the replenishing liquid tank 117, the sulfuricacid Q15 supplied from the sulfuric acid tank 118, and the hydrochloricacid Q16 supplied from the hydrochloric acid tank 119 so as to adjustthe components of the plating liquid Q17 in the plating liquid adjustingtank 113.

The plating liquid managing apparatus thus constructed operates asfollows: When a plating process is to be started, certain amounts ofreplenishing liquids Q12, Q13, Q14 with the additives A, B, C mixedtherewith may be added to the standard liquid Q11 from the standardliquid tank 114. The automatic analyzing device 122 automaticallyanalyzes the concentrations of the additive A (polymer), the additive B(carrier), and the additive C (leveler), as described above, and alsoautomatically analyzes the concentrations of Cu2+, H2SO4, and Cl—. Theseconcentrations may automatically be analyzed according to a titrimetricanalyzing process or a spectrophotometric analyzing process.

At the time of starting the plating process, since a variation of theconcentrations of the components vary greatly, the sampling frequencyfor sampling the plating liquid with the sampling device 121 is set to ahigh value. While in the plating process, the replenishing liquids Q12,Q13, Q14 and the hydrochloric acid Q16 are individually supplied to theplating liquid Q17 in the plating liquid adjusting tank 113 in order tokeep the concentrations of the components within a certain managementrange depending on the analyzed results from the automatic analyzingdevice 122.

When the concentrations of the components are stabilized, the samplingfrequency for sampling the plating liquid with the sampling device 121is set to a lower value, e.g., once every few hours. At this time, aprocess of supplying the replenishing liquids Q12, Q13, Q14 from thereplenishing liquid tanks 115, 116, 117 at predetermined periods of timemay be combined to compensate for the consumed amounts of additives thatare empirically known depending on the quantity of electricity.

The plating liquid Q in the plating tank 110 is partly removed out ofthe system depending on the number of substrates 112 that are plated.The consumption of the components of the additives is also substantiallyproportional to the number of substrates 112 that are plated (integratedcurrent value). Therefore, the removed amount of plating liquid andchanges in the volumes of the additives can be kept in balance byproperly adjusting in advance the concentrations of the components to beadded.

For example, if the additives A, B, C are to be uniformly replenished,then the concentrations of the replenishing liquids Q12, Q13, Q14 aregiven as follows:Concentration of an additive (mg/ml) in the component replenishingliquid=consumed amount (mg)/[removed amount×⅓ (ml)]

Actually, since the components in the plating liquid are reduced influctuations, the concentrations are made greater than, (e.g., abouttwice), the concentration given by the above equation, and the amountsof the component replenishing liquids of the additives are reduced andthe replenishing liquid Q11 is replenished as the remainder. In thismanner, the replenishing liquids in the adjusting tanks are preventedfrom being excessive.

With the above method of and apparatus for managing the plating liquid,as described above, component replenishing liquids comprise a standardliquid, a plurality of solutions of a basic liquid with a plurality ofdifferent additives added thereto, sulfuric acid, and hydrochloric acid,either wholly or partly. The component replenishing liquids are suppliedto a plating liquid by a component replenishing liquid supply device.The additive can easily be managed individually, and the concentrationsof the components can be managed more strictly. Thus, it is possible toproduce uniform and homogeneous films of plated copper to provide highlyreliable copper interconnections.

INDUSTRIAL APPLICABILITY

The present invention can be used to measure the concentration of aleveler in a plating liquid that is used by a plating apparatus forfilling metal such as copper in interconnection trenches and holesdefined in the surface of a semiconductor substrate or the like, andalso to manage a plating liquid to manage the components thereof.

1-2. (canceled)
 3. An apparatus for managing the components of a platingliquid in a plating apparatus which immerses a substrate to be plated inthe plating liquid in a plating tank to plate a surface of thesubstrate, the apparatus having a plating liquid sampling device forsampling a predetermined amount of the plating liquid at a predeterminedinterval, an automatic analyzing device for automatically analyzing thecomponents of the plating liquid sampled by the plating liquid samplingdevice, and a component replenishing liquid supply device for supplyingcomponent replenishing liquids comprising the components of the platingliquid, wherein the component replenishing liquids are supplied to theplating liquid based on analyzed results from said automatic analyzingdevice and/or the number of substrates to be plated and a quantity ofelectricity consumed to plate the substrates for thereby managing thecomponents of the plating liquid, characterized in that the componentreplenishing liquids comprise a standard liquid, a plurality ofsolutions of a basic liquid with a plurality of different additivesadded thereto, sulfuric acid, and hydrochloric acid, either wholly orpartly, and the component replenishing liquids are supplied by thecomponent replenishing liquid supply device to the plating liquid forthereby individually replenishing and managing the components of theplating liquid.
 4. An apparatus according to claim 3, comprising: aplating liquid adjusting tank, separate from said plating tank, forsupplying the component replenishing liquids to said plating liquid.